#include <Windows.h>
#include "md5.h"

using namespace std;

/* Constants for MD5Transform routine. */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21


/* F, G, H and I are basic MD5 functions.
*/
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits.
*/
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
Rotation is separate from addition to prevent recomputation.
*/
#define FF(a, b, c, d, x, s, ac) { \
	(a) += F ((b), (c), (d)) + (x) + ac; \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
	(a) += G ((b), (c), (d)) + (x) + ac; \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
	(a) += H ((b), (c), (d)) + (x) + ac; \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
	(a) += I ((b), (c), (d)) + (x) + ac; \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
}


const byte MD5::PADDING[64] = { 0x80 };
const char MD5::HEX[16] =
{
    '0', '1', '2', '3',
    '4', '5', '6', '7',
    '8', '9', 'a', 'b',
    'c', 'd', 'e', 'f'
};


/* Default construct. */
MD5::MD5()
{
    reset();
}

/* Construct a MD5 object with a input buffer. */
MD5::MD5( const void* input, size_t length )
{
    reset();
    update( input, length );
}

/* Construct a MD5 object with a string. */
MD5::MD5( const string& str )
{
    reset();
    update( str );
}

/* Construct a MD5 object with a file. */
MD5::MD5( ifstream& in )
{
    reset();
    update( in );
}

/* Return the message-digest */
const byte* MD5::digest()
{

    if ( !_finished )
    {
        _finished = true;
        final();
    }
    return _digest;
}

/* Reset the calculate state */
void MD5::reset()
{

    _finished = false;
    /* reset number of bits. */
    _count[0] = _count[1] = 0;
    /* Load magic initialization constants. */
    _state[0] = 0x67452301;
    _state[1] = 0xefcdab89;
    _state[2] = 0x98badcfe;
    _state[3] = 0x10325476;
}

/* Updating the context with a input buffer. */
void MD5::update( const void* input, size_t length )
{
    update( ( const byte* )input, length );
}

/* Updating the context with a string. */
void MD5::update( const string& str )
{
    update( ( const byte* )str.c_str(), str.length() );
}

/* Updating the context with a file. */
void MD5::update( ifstream& in )
{

    if ( !in )
    {
        return;
    }

    std::streamsize length;
    char buffer[BUFFER_SIZE];
    while ( !in.eof() )
    {
        in.read( buffer, BUFFER_SIZE );
        length = in.gcount();
        if ( length > 0 )
        {
            update( buffer, length );
        }
    }
    in.close();
}

/* MD5 block update operation. Continues an MD5 message-digest
operation, processing another message block, and updating the
context.
*/
void MD5::update( const byte* input, size_t length )
{

    uint32 i, index, partLen;

    _finished = false;

    /* Compute number of bytes mod 64 */
    index = ( uint32 )( ( _count[0] >> 3 ) & 0x3f );

    /* update number of bits */
    if ( ( _count[0] += ( ( uint32 )length << 3 ) ) < ( ( uint32 )length << 3 ) )
    {
        ++_count[1];
    }
    _count[1] += ( ( uint32 )length >> 29 );

    partLen = 64 - index;

    /* transform as many times as possible. */
    if ( length >= partLen )
    {

        memcpy( &_buffer[index], input, partLen );
        transform( _buffer );

        for ( i = partLen; i + 63 < length; i += 64 )
        {
            transform( &input[i] );
        }
        index = 0;

    }
    else
    {
        i = 0;
    }

    /* Buffer remaining input */
    memcpy( &_buffer[index], &input[i], length - i );
}

/* MD5 finalization. Ends an MD5 message-_digest operation, writing the
the message _digest and zeroizing the context.
*/
void MD5::final()
{

    byte bits[8];
    uint32 oldState[4];
    uint32 oldCount[2];
    uint32 index, padLen;

    /* Save current state and count. */
    memcpy( oldState, _state, 16 );
    memcpy( oldCount, _count, 8 );

    /* Save number of bits */
    encode( _count, bits, 8 );

    /* Pad out to 56 mod 64. */
    index = ( uint32 )( ( _count[0] >> 3 ) & 0x3f );
    padLen = ( index < 56 ) ? ( 56 - index ) : ( 120 - index );
    update( PADDING, padLen );

    /* Append length (before padding) */
    update( bits, 8 );

    /* Store state in digest */
    encode( _state, _digest, 16 );

    /* Restore current state and count. */
    memcpy( _state, oldState, 16 );
    memcpy( _count, oldCount, 8 );
}

/* MD5 basic transformation. Transforms _state based on block. */
void MD5::transform( const byte block[64] )
{

    uint32 a = _state[0], b = _state[1], c = _state[2], d = _state[3], x[16];

    decode( block, x, 64 );

    /* Round 1 */
    FF ( a, b, c, d, x[ 0], S11, 0xd76aa478 ); /* 1 */
    FF ( d, a, b, c, x[ 1], S12, 0xe8c7b756 ); /* 2 */
    FF ( c, d, a, b, x[ 2], S13, 0x242070db ); /* 3 */
    FF ( b, c, d, a, x[ 3], S14, 0xc1bdceee ); /* 4 */
    FF ( a, b, c, d, x[ 4], S11, 0xf57c0faf ); /* 5 */
    FF ( d, a, b, c, x[ 5], S12, 0x4787c62a ); /* 6 */
    FF ( c, d, a, b, x[ 6], S13, 0xa8304613 ); /* 7 */
    FF ( b, c, d, a, x[ 7], S14, 0xfd469501 ); /* 8 */
    FF ( a, b, c, d, x[ 8], S11, 0x698098d8 ); /* 9 */
    FF ( d, a, b, c, x[ 9], S12, 0x8b44f7af ); /* 10 */
    FF ( c, d, a, b, x[10], S13, 0xffff5bb1 ); /* 11 */
    FF ( b, c, d, a, x[11], S14, 0x895cd7be ); /* 12 */
    FF ( a, b, c, d, x[12], S11, 0x6b901122 ); /* 13 */
    FF ( d, a, b, c, x[13], S12, 0xfd987193 ); /* 14 */
    FF ( c, d, a, b, x[14], S13, 0xa679438e ); /* 15 */
    FF ( b, c, d, a, x[15], S14, 0x49b40821 ); /* 16 */

    /* Round 2 */
    GG ( a, b, c, d, x[ 1], S21, 0xf61e2562 ); /* 17 */
    GG ( d, a, b, c, x[ 6], S22, 0xc040b340 ); /* 18 */
    GG ( c, d, a, b, x[11], S23, 0x265e5a51 ); /* 19 */
    GG ( b, c, d, a, x[ 0], S24, 0xe9b6c7aa ); /* 20 */
    GG ( a, b, c, d, x[ 5], S21, 0xd62f105d ); /* 21 */
    GG ( d, a, b, c, x[10], S22,  0x2441453 ); /* 22 */
    GG ( c, d, a, b, x[15], S23, 0xd8a1e681 ); /* 23 */
    GG ( b, c, d, a, x[ 4], S24, 0xe7d3fbc8 ); /* 24 */
    GG ( a, b, c, d, x[ 9], S21, 0x21e1cde6 ); /* 25 */
    GG ( d, a, b, c, x[14], S22, 0xc33707d6 ); /* 26 */
    GG ( c, d, a, b, x[ 3], S23, 0xf4d50d87 ); /* 27 */
    GG ( b, c, d, a, x[ 8], S24, 0x455a14ed ); /* 28 */
    GG ( a, b, c, d, x[13], S21, 0xa9e3e905 ); /* 29 */
    GG ( d, a, b, c, x[ 2], S22, 0xfcefa3f8 ); /* 30 */
    GG ( c, d, a, b, x[ 7], S23, 0x676f02d9 ); /* 31 */
    GG ( b, c, d, a, x[12], S24, 0x8d2a4c8a ); /* 32 */

    /* Round 3 */
    HH ( a, b, c, d, x[ 5], S31, 0xfffa3942 ); /* 33 */
    HH ( d, a, b, c, x[ 8], S32, 0x8771f681 ); /* 34 */
    HH ( c, d, a, b, x[11], S33, 0x6d9d6122 ); /* 35 */
    HH ( b, c, d, a, x[14], S34, 0xfde5380c ); /* 36 */
    HH ( a, b, c, d, x[ 1], S31, 0xa4beea44 ); /* 37 */
    HH ( d, a, b, c, x[ 4], S32, 0x4bdecfa9 ); /* 38 */
    HH ( c, d, a, b, x[ 7], S33, 0xf6bb4b60 ); /* 39 */
    HH ( b, c, d, a, x[10], S34, 0xbebfbc70 ); /* 40 */
    HH ( a, b, c, d, x[13], S31, 0x289b7ec6 ); /* 41 */
    HH ( d, a, b, c, x[ 0], S32, 0xeaa127fa ); /* 42 */
    HH ( c, d, a, b, x[ 3], S33, 0xd4ef3085 ); /* 43 */
    HH ( b, c, d, a, x[ 6], S34,  0x4881d05 ); /* 44 */
    HH ( a, b, c, d, x[ 9], S31, 0xd9d4d039 ); /* 45 */
    HH ( d, a, b, c, x[12], S32, 0xe6db99e5 ); /* 46 */
    HH ( c, d, a, b, x[15], S33, 0x1fa27cf8 ); /* 47 */
    HH ( b, c, d, a, x[ 2], S34, 0xc4ac5665 ); /* 48 */

    /* Round 4 */
    II ( a, b, c, d, x[ 0], S41, 0xf4292244 ); /* 49 */
    II ( d, a, b, c, x[ 7], S42, 0x432aff97 ); /* 50 */
    II ( c, d, a, b, x[14], S43, 0xab9423a7 ); /* 51 */
    II ( b, c, d, a, x[ 5], S44, 0xfc93a039 ); /* 52 */
    II ( a, b, c, d, x[12], S41, 0x655b59c3 ); /* 53 */
    II ( d, a, b, c, x[ 3], S42, 0x8f0ccc92 ); /* 54 */
    II ( c, d, a, b, x[10], S43, 0xffeff47d ); /* 55 */
    II ( b, c, d, a, x[ 1], S44, 0x85845dd1 ); /* 56 */
    II ( a, b, c, d, x[ 8], S41, 0x6fa87e4f ); /* 57 */
    II ( d, a, b, c, x[15], S42, 0xfe2ce6e0 ); /* 58 */
    II ( c, d, a, b, x[ 6], S43, 0xa3014314 ); /* 59 */
    II ( b, c, d, a, x[13], S44, 0x4e0811a1 ); /* 60 */
    II ( a, b, c, d, x[ 4], S41, 0xf7537e82 ); /* 61 */
    II ( d, a, b, c, x[11], S42, 0xbd3af235 ); /* 62 */
    II ( c, d, a, b, x[ 2], S43, 0x2ad7d2bb ); /* 63 */
    II ( b, c, d, a, x[ 9], S44, 0xeb86d391 ); /* 64 */

    _state[0] += a;
    _state[1] += b;
    _state[2] += c;
    _state[3] += d;
}

/* Encodes input (ulong) into output (byte). Assumes length is
a multiple of 4.
*/
void MD5::encode( const uint32* input, byte* output, size_t length )
{

    for ( size_t i = 0, j = 0; j < length; ++i, j += 4 )
    {
        output[j] = ( byte )( input[i] & 0xff );
        output[j + 1] = ( byte )( ( input[i] >> 8 ) & 0xff );
        output[j + 2] = ( byte )( ( input[i] >> 16 ) & 0xff );
        output[j + 3] = ( byte )( ( input[i] >> 24 ) & 0xff );
    }
}

/* Decodes input (byte) into output (ulong). Assumes length is
a multiple of 4.
*/
void MD5::decode( const byte* input, uint32* output, size_t length )
{

    for ( size_t i = 0, j = 0; j < length; ++i, j += 4 )
    {
        output[i] = ( ( uint32 )input[j] ) | ( ( ( uint32 )input[j + 1] ) << 8 ) |
                    ( ( ( uint32 )input[j + 2] ) << 16 ) | ( ( ( uint32 )input[j + 3] ) << 24 );
    }
}

/* Convert byte array to hex string. */
string MD5::bytesToHexString( const byte* input, size_t length )
{

    string str;
    str.reserve( length << 1 );
    for ( size_t i = 0; i < length; ++i )
    {
        int t = input[i];
        int a = t / 16;
        int b = t % 16;
        str.append( 1, HEX[a] );
        str.append( 1, HEX[b] );
    }
    return str;
}

/* Convert digest to string value */
string MD5::toString()
{
    return bytesToHexString( digest(), 16 );
}
